Visible light communications (VLC) is a communications medium that uses visible light (e.g., light with wavelengths in the range of approximately 400 to 700 nanometers (nm) that may be seen with the naked human eye) to wirelessly transmit data (e.g., voice data, numerical data and image data). To transmit data using VLC, a visible light source, such as a fluorescent light bulb or a light emitting diode (LED), may be turned on and off or intensity modulated at a very high speed. A receiving device (e.g., a camera, a mobile telephone's imager or ambient light sensor) may receive the intensity modulated light and convert it into data that the receiving device may process for the user's use and/or enjoyment.
One major draw to VLC is the ubiquitous nature of visible light sources that may be used to transmit data to receiving devices. By way of example, lamps, consumer electronics which may include LED backlit displays and other LEDs, such as indicator lights and traffic signals, all include one or more visible light sources. Thus, visible light sources have the potential to wirelessly transmit data to a user located almost anywhere.
VLC may provide benefits such as freeing up limited radio frequency bandwidth for other uses since it does not require use of a radio frequency bandwidth. In addition, since light sources are already in place for other purposes (e.g., providing light and displaying television shows, movies and data), the light sources may be readily converted into transmitters by simply coupling them to control devices. However, one drawback to VLC is that VLC may interfere with dimming.
VLC may be used in a variety of applications, including but not limited to the categories listed in Table 1 below.
TABLE 1ApplicationNodeDefinitionExamplesInfrastructureNetworkedVLAN, ATMcommunications nodeMachineinstalled at a permanentlocationMobileLow mobility device,PDAmay include fixeddevicesVehicularHigh mobility nodeAutomobileassociated withtransportationapplications